Fluid reservoir

ABSTRACT

A power assist system for a motor vehicle subsystem having a component support structure is described. The power assist system comprises a fluid reservoir, a pump having an inlet for receiving a fluid from the reservoir and a pump securing structure including at least one aperture. The system additionally includes at least one fastener. The reservoir fluid outlet is directly coupled to the pump inlet and the at least one fastener secures the reservoir mounting structure by passing directly through the pump mounting structure and attaching to the motor vehicle component support structure.

This application is a divisional of co-pending U.S. application Ser. No.11/245,918 filed on 7 Oct. 2005, herein incorporated by reference in itsentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fluid power assist system for a motorvehicle. More specifically, this invention relates to a fluid powerassist system having a fluid reservoir in cooperation with a pump for amotor vehicle.

2. Prior Art

Conventional vehicles employ power assistance systems in many ways.Power assisted brakes and power assisted steering are just two of suchapplications. Power assisted steering systems are systems in which thesteering force is produced by the driver's muscular energy and by anenergy source within the vehicle. For this purpose, a hydraulic oil,which is pressurized by means of a pump and serves to generate orincrease the steering power, is provided in a closed system. Powerassisted brakes work in a similar manner. The energy source may comprisea vacuum booster for a brake system or a pump driven by flywheel for asteering system. These systems typically include an oil reservoir andthe corresponding hoses and pipes which transfer the fluid through thesystem.

Conventional vehicle power steering systems may mount the oil reservoiron the body structure underneath the hood. In these systems, the powersteering oil or fluid is typically collected in the power steering oilreservoir after its use by the steering gear and then supplied to thepump through a large diameter suction hose. The design of this systemhas its drawbacks. First, the suction hose offers poor under hoodappearance. Competition between Original Equipment Manufacturers (OEMs)is fierce in today's marketplace. Under-hood craftsmanship is anotherarea in which OEMs can attempt to differentiate their brand. Second, thesuction hose is a costly item. The under-hood hose material is oftenrequired to have increased durability and performance requirements.These hoses are often long and must be formed in order to effectivelynegotiate other components located in the engine compartment. Theforming also increases its piece cost. The size of the suction hoserequires additional fluid in the system in order to operate the steeringsystem. The assembly costs are increased because of the size of thehoses and overall system, more evacuation and field time is required inthe assembly plant. Third, power steering hoses also provideopportunities for leakage which can be a nagging warranty item. Finally,the more fluid required to be pushed through the system requires moreenergy and adds to fluid consumption. Therefore, what is needed is apower assist system which is better designed for assembly and reduceslabor time, eliminates unnecessary parts, reduces warranty, improvesunder hood appearance, and offers a more efficient and cost savingsystem.

SUMMARY OF THE INVENTION

According to the present invention, a power assist system for a motorvehicle subsystem, the motor vehicle having a component supportstructure comprises a fluid reservoir having a reservoir fluid outlet, areturn fluid inlet for receiving fluid, and a reservoir mountingstructure. The power assist system further comprises a pump having aninlet for receiving the fluid from the reservoir, a pump outlet forproviding the fluid, and a pump securing structure including at leastone aperture. Additionally, the system includes at least one fastenerfor securing the reservoir mounting structure to the motor vehiclecomponent support structure. The fastener secures the reservoir mountingstructure by passing directly through the pump securing structureaperture and attaching to the component support structure.

The invention has the advantage of removing costs from a vehicle's powerassist system. The elimination of the main suction hose, the hose'sassociated clamps, as well as a reservoir mounting bracket, result in asmaller and more efficient system. In contrast, the conventional systemresults in a suction hose full of fluid. In the preferred embodiment,the amount of fluid required in the overall system is reduced as well.

The invention has the further advantage of providing a more efficientand flexible power assist system without realizing the high costs ofdevelopment that accompany the redesign of a conventional variabledisplacement pump integral to power assist systems. The power assistsystem described here takes advantage of an existing pump design andmounts the reservoir mounting structure by passing directly through thepump securing structure aperture and attaching to the component supportstructure. Although many of the pumps having reservoirs directlyintegrated into their housing exist today to provide space savings, thesavings come with disadvantages of a high cost and a loss offlexibility. The cost associated with retooling and redesigning themolds for a pump to make the reservoir an integral part of a pump is asignificant amount. Additionally, in the undesired circumstance that thereservoir portion fails, there is no way to “limp home” since removingthe reservoir renders the pump useless. In contrast, the systemdescribed herein allows for the old reservoir to be removed and atemporary reservoir to be substituted into the system with hoses andclamps, etc. For work vehicles such as trucks and farm equipment used inremote locations, the flexibility of a vehicle subsystem is oftenbeneficial.

According to a further object of the present invention, a method ofproviding a reservoir for a fluid power assist system in a motor vehiclehaving a component support structure is attained. The fluid power assistsystem has a pump and at least one reservoir fastener. The reservoir hasa chamber, a reservoir fluid supply outlet, a fluid return inlet, and areservoir mounting including a securing aperture. The pump includes apump securing structure containing an aperture, a pump inlet. The methodcomprises the steps of directly coupling the reservoir fluid supplyoutlet port to the pump inlet, aligning axially the reservoir mountingsecuring aperture and the pump mounting aperture, inserting one end ofthe reservoir fastener through both the reservoir mounting securingaperture and the pump mounting aperture to the motor vehicle componentsupport structure, and securing the reservoir fastener into the motorvehicle component support structure.

According to a further object of the present invention, a reservoir fora pump having a fluid inlet and a pump mounting structure containing atleast one securing aperture comprises an internal fluid chamber, a fluidoutlet, and a reservoir mounting structure having a securing aperture.The reservoir fluid outlet connects directly to the pump fluid inlet andthe reservoir securing aperture aligns with one of the at least pumpsecuring apertures.

The invention has the further advantage of reducing plant labor time.The elimination of the reservoir mounting bracket and the suction hoseand its corresponding clamps, results in fewer parts to assemble.Furthermore, since one reservoir fluid outlet connects directly to thepump fluid inlet and the reservoir surface is in close proximity to thea pump surface, the two components tend to orient themselves intoposition during loose assembly allowing the reservoir and the pump to beassembled into final position without additional clamping.

The invention has the further advantage of improving the under hoodappearance of the power assist system. The removal of the formed suctionhose provides a simple, compact system with improved underhoodcraftsmanship.

The invention has the further advantage of providing improving the powerassist system while maintaining the flexibility to end user of the motorvehicle in the event of a reservoir failure of the power assist systemin the field. Because the reservoir is not integrated into the housingof the pump, the power assist system will still function if suppliedwith fluid. In the event the reservoir fails in the field, it can betemporarily replaced by a conventional reservoir that can receive andsupply fluid to the system using conventional pipes and suction hoses.For commercial vehicles operating in remote locations, the ability toreduce the time and expense to recover a stranded vehicle is of value.

The above and other objects, features, and advantages of the presentinvention will become more apparent for the following description whentaken in conjunction with the accompanying drawings in which a preferredembodiment of the present invention is shown by way of the illustrativeexamples.

BRIEF DESCRIPTION OF THE DRAWINGS

Presently preferred embodiments of the invention are disclosed in thefollowing description and in the accompanying drawings, wherein:

FIG. 1 is a schematic diagram of a prior art power assist system;

FIG. 2 is a schematic diagram of one embodiment of a power assist systemaccording to the invention;

FIG. 3 is a side view of a fluid reservoir according to the invention;

FIG. 4 is an exploded view of a portion of a power assist systemaccording to the invention;

FIG. 5 is a perspective view of a portion of a power assist systemaccording to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a prior art power assist system 10 is schematicallyshown comprising a pump 12 for supplying a motor vehicle subsystem 14with fluid 15 using a high pressure line 16. Pump 12 may be a variabledisplacement or a positive fixed hydraulic pump such as a power steeringpump, oil pump, transmission pump, etc. A return line 20 transfers fluid15 between the motor vehicle subsystem 14 and a reservoir 22. Anoptional cooler 18 is often found in such systems to reduce thetemperature of the fluid 15 exiting the motor vehicle subsystem 14 andprior to returning to the reservoir 22. The reservoir 22 is typicallysecured to a first vehicle component support structure 24 such as avehicle body, frame or a portion of an engine using reservoir fasteners25. The reservoir fasteners 25 may be bolts, such as hex head carriagebolts, screws, or any other conventional fastener. Supply line 26provides fluid 15 returned or stored in the reservoir 22 to pump 12. Thesupply line 26 may be a suction hose in conventional vehicles. The pump12 is secured to a second vehicle component support structure 13 usingpump fasteners 17. In a conventional motor vehicle, the first vehiclecomponent support structure 24 and the second vehicle component supportstructure 13 are typically located in the engine compartment indistinctly separate locations. The pump 12 is typically powered thru apulley connected to the engine 28. In the alternative, an electric motormay be used to supply power to the pump 12. Similar to the first vehiclesupport structure 24, the second vehicle support structure 13 may be abracket formed by body or frame structure, or some other vehiclecomponent, such as engine 28. The motor vehicle subsystem 14 may be asteering gear of a power steering system, a power brake system, or othersuch type of system.

FIG. 2 is a schematic diagram of a power assist system according to thepresent invention. A power assist system 100 comprises a pump 102providing a volume of high pressure fluid 103 to a motor vehiclesubsystem 104 by means of a high pressure line 106. The high pressureline is a conventional pressure line and may be a pipe made of a metalmaterial. Pump 102 may be powered by an engine 114 thru a pulley (notshown). In the alternative, the motor vehicle subsystem 104 may be asteering gear of a steering system, a brake system, or other motorvehicle subsystem 104 requiring power assistance. Fluid 103 is returnedthrough a return line 110 to a reservoir 112. The return line 115 may bea pipe fabricated out of a metal material. An optional cooler 108 mayexist in between the motor vehicle subsystem 104 and the reservoir 112to serve as a conventional heat exchanger in order to reduce thetemperature of the fluid 103 prior to entry into the reservoir 112. Thereservoir 112 has an exterior surface 113 in close proximity with asurface 115 of the pump such that both surfaces abut against each other.An interface connection 111 between the pump 102 and the reservoir 112allows the fluid 103 to transfer directly from inside the reservoir 112to inside the pump 102 without need for a suction hose. Reservoir 112 issecured in place by one or more fasteners 146 passing through a portionof the reservoir 112, a portion of the pump 102, and received by avehicle component support structure 150.

Referring now to FIGS. 3-5, FIG. 3 is a side view of reservoir 112according to one embodiment of the present invention. An upper portion131 of the reservoir is formed in a rectangular shape and comprises aninternal chamber 140 for containing the bulk of the fluid. Inside thereservoir 112, a strainer 121 is located for filtering fluid. A fillerneck 124 is located on a top surface 126 to allow additional fluidneeded by the system to be poured from above the reservoir 112 into thechamber 140. The reservoir 112 may be sealed by a cap 128 or similarfunctional component. Optionally, one surface of the chamber 120 maycomprise a fill max and min indicator 142 to aid in adding additionalfluid 103. Alternatively, a fill indicator may be included as a portionof cap 128.

Reservoir 112 is constructed of man-made materials such as aglass-filled nylon. The exterior of the upper and lower portions 131,132 may be injection molded. In the alternative other molding methodssuch as cold molding processes may be used.

A lower portion of the reservoir 132 comprises a reservoir fluid outletport 134 and a return inlet 136. The lower portion 132 is smaller insize compared to the upper portion 131 and formed toward one end of thereservoir 112. The relationship between lower portion 132 and upperportion 131 aids in allowing the fluid outlet port 134 to have clearanceto a pump connection. The reservoir fluid outlet port 134 extends awayfrom the lower portion 132 to allow for an interface with a pump (notshown). The outlet port 134 may be formed with a circular end andcomprise a seat 135 for use in combination with an o-ring. The reservoirfluid outlet 134 is formed to allow for a flush mating connection with apump inlet port (not shown) to provide for the discharge of fluid to thepump. A reservoir return inlet 136 extends from a bottom surface 139 forreceiving pressurized fluid from a return line from a motor vehiclesystem.

The upper and lower portion 131, 132 respectively are formed and adaptedto aid in the mounting and securing of the reservoir in close proximityto a pump. An exterior surface of the reservoir 122 is formed by theupper portion 131 and the lower portion 132 to allow the reservoir toalign itself with relevant portions of the pump. The reservoir 112 has amounting structure 130 adapted for securing the reservoir in closeproximity to the pump. The mounting structure 130 comprises a twovertical elements extending from upper portion 131. A reservoir mountingaperture 129 is present in each vertical element to aid in securing thereservoir 112. Apertures 129 allow fasteners 146 to pass through andsecure the reservoir 112 in place. Surface 122 extends horizontallyalong the lower portion 132 to forms a clearance for one of thefasteners 146 to one of the apertures 129 located in the mountingstructure 130. A surface 125 is similarly formed to provide clearancefor one of the fasteners 146 which extends horizontally along the lowerportion 132 in a lower vertical plane arranged parallel to surface 122.

Referring to FIG. 4, an exploded view of an embodiment of a pump 102 andreservoir 112 according to the invention is described. Pump 102 iscylinder-shaped body shown powered by a belt 152 connected to a motorvehicle engine (not shown) thru a pulley 116. The pump is supported by avehicle component support structure 150 in the form of a body supportpanel. In an alternative embodiment, the vehicle component supportstructure 150 may be a firewall or body-in-white framing made from sheetmetal. Pump inlet port 138 is a circular-shaped female connecterextending horizontally from the pump 102. Pump securing structures 148extend horizontally along an upper surface 154 of the pump 102. The pumpsecuring structures 148 are each defined by an aperture 144 and acylindrical passage 156 extending throughout its length.

When reservoir 112 is in its ideal final position, the mountingapertures 129 of the reservoir mounting structure 130 are aligned withpump securing apertures 144. Reservoir exterior surface 122 is in closeproximity with the securing structure 148 of the pump 102. The exteriorsurface 122 is formed to allow it to lie beside the pump securingstructures 148. The fluid outlet port 134 engages pump inlet port 138.The connection allows fluid to transfer directly from the reservoir 112to inside the pump 102 without need for a suction hose. An o-ring orsimilar may be used in combination with the fluid outlet 134 to providea seal for the press or slip-fit connection. Reservoir 112 is secured inplace by one or more fasteners 146 passing through a reservoir throughreservoir mounting apertures 129 and through the pump securing apertures144. Each of the fasteners 146 is received by the vehicle componentsupport structure 150, thereby securing the reservoir 112.

FIG. 5 is a perspective view of a fluid reservoir of a power assistsystem according to the invention. The reservoir 112 is shown in anoperable position located behind the pulley 116 of a pump 102. Reservoir112 is adapted to lie beside or abut against an external surface of thepump (not shown). By aligning the reservoir 112 to lie beside a surfaceof the pump, reservoir fluid outlet and the pump fluid inlet are broughtinto close proximity to each other and the need for a long suction hosebetween the reservoir and the pump is further eliminated. The returnline 110 returns fluid 103 to the reservoir through a return inlet 136located on a lower portion 132 of the reservoir 112.

A method of providing fluid for a power assist system in a motor vehiclewill now be further described. First the reservoir fluid supply outletport is coupled directly to the pump inlet port. Next, the reservoirmounting structure aperture is aligned with the pump securing structureaperture in order to receive the reservoir fasteners. Third, one end ofthe reservoir fastener is inserted through both the aligned portions ofthe reservoir mounting structure aperture and the pump securingstructure aperture. Fourth, the reservoir fastener is secured to themotor vehicle component support structure.

Although there have been described what are at present considered to bethe preferred embodiments of the invention, it will be understood thatthe invention may be embodied in other specific forms without departingfrom the essential characteristics disclosed. The present embodiment isto be considered in all respects as illustrative, and not restrictive.The scope of the invention is indicated by the claims which followrather than by the foregoing description.

1. A reservoir for a pump, the pump comprising a fluid inlet and a pump mounting structure having at least one securing aperture, the reservoir comprising: an internal fluid chamber; a fluid outlet; and a reservoir mounting structure having a securing aperture; wherein the reservoir fluid outlet connects directly to the pump fluid inlet and the reservoir securing aperture aligns with one of the at least pump securing apertures.
 2. The reservoir of claim 1, wherein the reservoir mounting securing aperture abuts one pump securing aperture.
 3. The reservoir of claim 1, further comprising at least one external surface of the chamber wherein the at least one external surface is formed to lie beside the pump.
 4. The reservoir of claim 1, further comprising at least one external surface of the chamber is formed to but against a surface of the pump. 